sc16is7xx: fix Kconfig dependencies

When I2C=m and SPI=y or-ing them will produce =y while
what we need is the lower bound, i.e. =m.  Fortunately
SPI is a boolean so we need to handle only one special
case.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Jakub Kicinski <kubakici@wp.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/Kconfig

@@ -1185,7 +1185,7 @@ config SERIAL_SC16IS7XX_CORE
 config SERIAL_SC16IS7XX
         tristate "SC16IS7xx serial support"
         select SERIAL_CORE
-        depends on I2C || SPI_MASTER
+        depends on (SPI_MASTER && !I2C) || I2C
         help
           This selects support for SC16IS7xx serial ports.
           Supported ICs are SC16IS740, SC16IS741, SC16IS750, SC16IS752,